Levels Of Nitrogen Oxides Research Articles

How Covid-19 pandemic influenced air quality in Polish cities – lessons from three lockdowns

The aim of this study was to determine how COVID-19 pandemic influenced air quality in the chosen Polish cities. Data on nitrogen oxides, carbon monoxides, fine and coarse particulate matter concentrations from air quality monitoring stations was used to compare pollutants levels during the pandemic and in the 5-year pre-pandemic period. The impact of the pandemic on the air quality has been analysed using linear mixed effect models, adjusting for long-term, seasonal and weekly trends and meteorological conditions. Results showed that during the pandemic, until the second lockdown only nitrogen oxides levels were significantly reduced (up to 20%), while when again loosening restrictions the rebound effect led to 20-30% increase of all analysed pollutants.

Detection of Fuel Adulteration Using Wave Optical with Machine Learning Algorithms

Fuel is a very important factor and has considerable influence on the air quality in the environment, which is the heart of the world. The increase of vehicles in lived-in areas results in greater emission of carbon particles in the environment. Adulterated fuel causes more contaminated particles to mix with breathing air and becomes the main source of dangerous pollution. Adulteration is the mixing of foreign substances in fuel, which damages vehicles and causes more health problems in living beings such as humans, birds, aquatic life, and even water resources by emitting high levels of hydrocarbons, nitrogen oxides, and carbon monoxide. Most frequent blending liquids are lubricants and kerosene in the petrol, and its adulteration is a considerable problem that adds to environmental pollution. This study focuses on detecting the adulteration in petrol using sensors and machine learning algorithms. A modified evanescent wave optical fiber sensor with discrete wavelet transform is proposed for classification of adulterated data from the samples. Furthermore, support vector machine classifier is used for accurate categorization. The sensor is first tested with fuel and numerical data is classified based on machine learning algorithms. Finally, the result is evaluated with less error and high accuracy of 99.9%, which is higher than all existing techniques.

Experimental Investigations on exhaust emissions with an air gap insulated engine

Experiments were carried out to study exhaust emissions of diesel engine withair gap insulated low heat rejection (LHR–2) combustion chamber consisting of air gap insulated piston with 3mm air gap, with Superni (an alloy of nickel) crown and air gap insulated liner with superni insert with neat diesel with varied injection timing. Exhaust emissions of particulate emissions, nitrogen oxide (NOx) levels, carbon monoxide (CO) and un-burnt hydrocarbons (UBHC) were determined at various values of brake mean effective pressure (BMEP) of the LHR-2 combustion chamberand compared with neat diesel operation on conventional engine (CE) at similar operating conditions. The optimum injection timing was found to be 31obTDC (before top dead centre) with conventional engine, while it was 29obTDC for engine with LHR–2 combustion chamber with diesel operation. Engine with LHR–2 combustion chamber with neat diesel operation showed increased pollution levels at manufacturer’s recommended injection timing of 27obTDC, and they improved marginally with advanced injection timing of 29obTDC in comparison with CE at 27obTDC. The exhaust emissions from diesel engine cause health hazards and also environmental disorders. Hence, controlling of these emissions in an important and urgent step.

Total extract of Anemarrhenae Rhizoma attenuates bleomycin-induced pulmonary fibrosis in rats

Pulmonary fibrosis is a progressive interstitial lung disease with poor prognosis. Anemarrhenae Rhizoma is a traditional Chinese herbal medicine and has been applied in clinical practice for a long history. Recently, components of Anemarrhenae Rhizoma were reported to possess anti-inflammatory and immunomodulatory features; however, the effect of them on pulmonary fibrosis remains unknown. In this study, we explored the therapeutic effect of total extract of Anemarrhenae Rhizoma (TEAR) on bleomycin-induced pulmonary fibrosis. Pulmonary fibrosis rat model was established by a single intratracheal instillation of bleomycin, three doses of TEAR were intragastrically administered for consecutive 28 days. Subsequent to sacrificing of rats, pulmonary fibrosis was observed in rats treated with bleomycin, but administration of TEAR attenuated lung fibrosis, as evidenced by the improved lung histopathological damage and decreased weight loss and lung index. Moreover, TEAR treatment inhibited the inflammatory response in lung fibrosis, which was shown by the reduced nitrogen oxide level and myeloperoxidase activity. Furthermore, TEAR modulated the redox balance in lung tissue by alleviated lipid peroxidation and enhanced enzymatic antioxidants activity. Meanwhile, TEAR protected the rats from fibrosis in a dose-dependent manner, and the anti-fibrotic activity of TEAR may be related to the modulation of TGF-β1/Smad signaling pathway. Collectively, TEAR alleviates bleomycin-induced pulmonary fibrosis, indicating perspectives for development of a potential agent for lung fibrosis therapy.

Ozone chemistry in western U.S. wildfire plumes.

Wildfires are a substantial but poorly quantified source of tropospheric ozone (O3). Here, to investigate the highly variable O3 chemistry in wildfire plumes, we exploit the in situ chemical characterization of western wildfires during the FIREX-AQ flight campaign and show that O3 production can be predicted as a function of experimentally constrained OH exposure, volatile organic compound (VOC) reactivity, and the fate of peroxy radicals. The O3 chemistry exhibits rapid transition in chemical regimes. Within a few daylight hours, the O3 formation substantially slows and is largely limited by the abundance of nitrogen oxides (NOx). This finding supports previous observations that O3 formation is enhanced when VOC-rich wildfire smoke mixes into NOx-rich urban plumes, thereby deteriorating urban air quality. Last, we relate O3 chemistry to the underlying fire characteristics, enabling a more accurate representation of wildfire chemistry in atmospheric models that are used to study air quality and predict climate.

Engaging Social Science and Humanities Students in Community-Based Research on Nitrogen Oxide Pollution

A significant challenge to the community of chemistry education is the creation of materials that can be used in nonscience settings, including those of social science and humanities classrooms. As part of a larger effort to engage new communities in understanding how science data can impact such settings, including in the community, an experiment to detect the level of nitrogen oxides (NOx) in the air was implemented in university sociology and history classrooms. The use of an authentic scientific method within these settings generated important data for classroom use in classroom sociological and historical discussions. The impact on student attitudes and learning was also determined.

Indoor Air Pollution in Housing Units

Pollution and poor quality of the indoor environment is a common problem in today's residential buildings. These problems are reflected in the well-being and health of the users of these buildings. Targeted identification of the various harmful substances (pollutants) is essential for understanding the interactions of components of the internal environment for the welfare and health of building users. The Czech housing units were selected for screening investigation of indoor air quality. Measuring of indoor chemical factors was performed during the year 2019. The indoor levels of TVOC, nitrogen oxides, indoor radon, and particulate matters PM10 were measured. The results provide introduce data on indoor air quality concerning seasonal changes which were in correlation to air change rate. These results, introduced in this paper, help to understand the indoor pollutants occurrence and help to design next more focused studies.

An 18 year data-linkage study on the association between air pollution and acute limb ischaemia.

Background: There is limited information regarding the effects of air pollutants, such as nitrogen oxides (NOx), nitric oxide (NO2), nitrous oxide (NO) and particulate matter with a diameter smaller than 10 μm (PM10), on acute limb ischaemia (ALI), a peripheral arterial disease (PAD) often with a poor clinical outcome. Patients and methods: We conducted an 18-year retrospective cohort study using routinely collected healthcare records from Ninewells Hospital, Dundee, and Perth Royal Infirmary, in Tayside, Scotland, UK from 2000 to 2017. ALI hospitalisation events and deaths were linked to daily NOx, NO2, NO and PM10 levels extracted from publicly available data over this same time period. Distributed lag models were used to estimate risk ratios for ALI hospitalisation and for ALI mortality, adjusting for temperature, humidity, day of the week, month and public holiday. Results: 5,608 hospital admissions in 2,697 patients were identified over the study period (mean age 71.2 years, ±11.1). NOx and NO were associated with an increase of ALI hospital admissions on days of exposure to pollutant (p=.018), while PM10 was associated with a cumulative (lag 0-9 days) increase (p=.027) of ALI hospital admissions in our study. There was no increase of ALI mortality associated with pollution levels. Conclusions: ALI hospital admissions were positively associated with ambient NOx and NO on day of high measured pollution levels and a cumulative effect was seen with PM10.

MODEL OF NITROGEN OXIDE POLLUTION OF THE CITY MAINS

To manage the quality of atmospheric air in the city, it is of great importance to study the formation of extremely high atmospheric pollution. The preliminary assessment of atmospheric air pollution allows to determine the contribution of road transport emission sources, with the help of which it is possible to simulate a specific situation and to give predictive assessments of the state of atmospheric air pollution,
 as well as to determine the ways to improve the environmental characteristics of road transport, develop the city road network and other factors. The transport model of the city is one of the tools for strategic transport planning that allows for the justification and adoption of effective and responsible design decisions in the field of transport and infrastructure.
 The following data analysis on the available sources of atmospheric air pollution of the city mains has been performed: an assessment of the road transport intensity, an assessment of the amount of nitrogen oxides emissions, an assessment of the level of nitrogen oxides in the atmospheric air. Measurements have shown that the average concentrations of nitrogen oxides in places of intense anthropogenic load –the crossroads of city mains – are dozens of times higher than the maximum permissible concentration. Nearby the city mains and crossroads, the maximum concentrations of pollutants are formed at low wind speeds with wind directions at an angle close to 45° to the main areas.
 On the basis of the calculations, the following model of nitrogen oxide pollution of the city mains was obtained – the dependence of the concentration of nitrogen oxides on the road transport intensity can be a criterion for zoning the city territory according to the degree of atmospheric air pollution.

Investigation of Air Pollutants Related to the Vehicular Exhaust Emissions in the Kathmandu Valley, Nepal

The Kathmandu Valley, which is surrounded by high hills and mountains, has been plagued by air pollution, especially in winter. We measured the levels of volatile organic compounds, nitrogen dioxide, nitrogen oxides, sulfur dioxide, ammonia, ozone, PM2.5, and carbon monoxide in the Kathmandu Valley during the winter to investigate the impact of vehicular emissions and the contribution of gaseous air pollutants to secondary pollutants. The most common gaseous pollutants were discovered to be gasoline components, which were emitted more frequently by engine combustion than gasoline evaporation. Considering the ethylene to acetylene ratio, it was discovered that most vehicles lacked a well-maintained catalyst. Compared to previous studies, it was considered that an increase in the number of gasoline vehicles offset the effect of the measures and exceeded it, increasing the level of air pollutants. Aromatics and alkenes accounted for 66–79% and 43–59% of total ozone formation potential in Koteshwor and Sanepa, respectively. In terms of individual components, it was determined that ethylene, propylene, toluene, and m-xylene all significantly contributed to photochemical ozone production. As those components correlated well with isopentane, which is abundant in gasoline vehicle exhaust, it was determined that gasoline vehicles are the primary source of those components. It was indicated that strategies for regulating gasoline vehicle exhaust emissions are critical for controlling the photochemical smog in the Kathmandu Valley.

Personal exposure levels to O3, NOx and PM10 and the association to ambient levels in two Swedish cities

Exposure to air pollution is of great concern for public health although studies on the associations between exposure estimates and personal exposure are limited and somewhat inconsistent. The aim of this study was to quantify the associations between personal nitrogen oxides (NOx), ozone (O3) and particulate matter (PM10) exposure levels and ambient levels, and the impact of climate and time spent outdoors in two cities in Sweden. Subjects (n = 65) from two Swedish cities participated in the study. The study protocol included personal exposure measurements at three occasions, or waves. Personal exposure measurements were performed for NOx and O3 for 24 h and PM10 for 24 h, and the participants kept an activity diary. Stationary monitoring stations provided hourly data of NOx, O3 and PM, as well as data on air temperature and relative humidity. Data were analysed using mixed linear models with the subject-id as a random effect and stationary exposure and covariates as fixed effects. Personal exposure levels of NOx, O3 and PM10 were significantly associated with levels measured at air pollution monitoring stations. The associations persisted after adjusting for temperature, relative humidity, city and wave, but the modelled estimates were slightly attenuated from 2.4% (95% CI 1.8–2.9) to 2.0% (0.97–2.94%) for NOx, from 3.7% (95% CI 3.1–4.4) to 2.1% (95% CI 1.1–2.9%) for O3 and from 2.6% (95% 0.9–4.2%) to 1.3% (95% CI − 1.5–4.0) for PM10. After adding covariates, the degree of explanation offered by the model (coefficient of determination, or R2) did not change for NOx (0.64 to 0.63) but increased from 0.46 to 0.63 for O3, and from 0.38 to 0.43 for PM10. Personal exposure to NOx, O3 and PM has moderate to good association with levels measured at urban background sites. The results indicate that stationary measurements are valid as measure of exposure in environmental health risk assessments, especially if they can be refined using activity diaries and meteorological data. Approximately 50–70% of the variation of the personal exposure was explained by the stationary measurement, implying occurrence of misclassification in studies using more crude exposure metrics, potentially leading to underestimates of the effects of exposure to ambient air pollution.

Assessing the intra-urban variability of nitrogen oxides and ozone across a highly heterogeneous urban area.

High-resolution air quality maps are critical towards assessing and understanding exposures to elevated air pollution in dense urban areas. However, these surfaces are rarely available in low- and middle-income countries that suffer from some of the highest air pollution levels worldwide. In this study, we make use of land use regressions (LURs) to generate annual and seasonal, high-resolution nitrogen dioxide (NO2), nitrogen oxides (NOx), and ozone (O3) exposure surfaces for the Greater Beirut Area (GBA) in Lebanon. NO2, NOx and O3 concentrations were monitored using passive samplers that were deployed at 55 pre-defined monitoring locations. The average annual concentrations of NO2, NOx, and O3 across the GBA were 36.0, 89.7, and 26.9ppb, respectively. Overall, the performance of the generated models was appropriate, with low biases, high model robustness, and acceptable R2 values that ranged between 0.66 and 0.73 for NO2, 0.56 and 0.60 for NOx, and 0.54 and 0.65 for O3. Traffic-related emissions as well as the operation of a fossil-fuel power plant were found to be the main contributors to the measured NO2 and NOx levels in the GBA, whereas they acted as sinks for O3 concentrations. No seasonally significant differences were found for the NO2 and NOx pollution surfaces; as their seasonal and annual models were largely similar (Pearson's r > 0.85 for both pollutants). On the other hand, seasonal O3 pollution surfaces were significantly different. The model results showed that around 99% of the population of the GBA were exposed to NO2 levels that exceeded the World Health Organization defined annual standard.

Acute effects of ambient nitrogen oxides and interactions with temperature on cardiovascular mortality in Shenzhen, China

BackgroundThough inconsistent, acute effects of ambient nitrogen oxides on cardiovascular mortality have been reported. Whereas, interactive roles of temperature on their relationships and joint effects of different indicators of nitrogen oxides were less studied. This study aimed to extrapolate the independent roles of ambient nitrogen oxides and temperature interactions on cardiovascular mortality. MethodsData on mortality, air pollutants, and meteorological factors in Shenzhen from 2013 to 2019 were collected. Three indicators including nitric oxide (NO), nitrogen dioxide (NO2), and nitrogen oxides (NOX) were studied. Adjusted generalized additive models (GAMs) were applied to analyse their associations with cardiovascular mortality in different groups. ResultsThe average daily concentrations of NO, NO2, and NOX were 11.7 μg/m3, 30.7 μg/m3, and 53.2 μg/m3, respectively. Significant associations were shown with each indicator. Cumulative effects of nitrogen oxides were more obvious than distributed lag effects. Males, population under 65 years old, and population with stroke-related condition were more susceptible to nitrogen oxides. Adverse effects of nitrogen oxides were more significant at low temperature. Impacts of NO2 on cardiovascular mortality, and NO on stroke mortality were the most robust in the multi-pollutant models, whereas variations were shown in the other relationships. ConclusionsLow levels of nitrogen oxides showed acute and adverse impacts and the interactive roles of temperature on cardiovascular mortality. Cumulative effects were most significant and joint effects of nitrogen oxides required more attention. Population under 65 years old and population with stroke-related health condition were susceptible, especially days at lower temperature.

Improving the usage of vegetable oils in generator sets used for off-grid power generation by hydrogen addition

This study experimentally investigates the effects on the performance and combustion process of a diesel generator set operating with blends of 20 and 50% of vegetable oil (V20 and V50) in B7 (volumetric mixture of 7% biodiesel with 93% diesel fuel) and with addition of hydrogen in the air intake. Hydrogen was injected continuously into the plenum at various volumetric flow rates (2.7, 6.5, 7.7, 8.5, 11.4, and 14.3 l/min). Results showed an improvement in the engine performance when increasing the hydrogen addition, reducing the specific fuel consumption, and decreasing its effective thermal efficiency. In the same way, the CO2, CO and HC emissions concentration decreased proportionally as the hydrogen concentration was increased. On the other hand, the levels of nitrogen oxides (NOx) increased due to the higher in-cylinder average temperature. In the combustion process, the maximum pressure peak and the rate of heat release inside the cylinder increased in, since the ignition delay for both mixtures (V20 and V50) reduced, also reduces the combustion duration due to the increasing on hydrogen addition.

Study of different Carbon Bond 6 (CB6) mechanisms by using a concentration sensitivity analysis

Abstract. Since the year 2010, different versions of the Carbon Bond 6 (CB6) mechanism have been developed to accurately estimate the contribution to air pollution by the chemistry. In order to better understand the differences in simulation results brought about by the modifications between different versions of the CB6 mechanism, in the present study, we investigated the behavior of three different CB6 mechanisms (CB6r1, CB6r2 and CB6r3) in simulating ozone (O3), nitrogen oxides (NOx) and formaldehyde (HCHO) under two different emission conditions by applying a concentration sensitivity analysis in a box model. The results show that when the surface emission is weak, the O3 level predicted by CB6r1 is approximately 7 ppb higher than that predicted by CB6r2 and CB6r3, specifically due to the change in the sink of acyl peroxy radicals with high-order carbons (i.e., species CXO3) in the mechanism and the difference in the ozone dependence on the isoprene emission. In contrast, although CB6r1 estimates higher values of NOx and HCHO than the other two mechanisms at an early stage of the simulation, the levels of NOx and HCHO estimated by these three CB6 mechanisms at the end of the 7 d simulation are mostly similar, when the surface emission is weak. After the increase in the surface emission, the simulated profiles of O3, NOx and HCHO obtained by CB6r2 and CB6r3 were found to be nearly the same during the simulation period, but CB6r1 tends to estimate substantially higher values than CB6r2 and CB6r3. The deviation between the O3 levels provided by CB6r1 and the other two CB6 mechanisms (i.e., CB6r2 and CB6r3) was found to be enlarged compared with the weak-emission scenario because of the weaker dependence of ozone on the emission of isoprene in CB6r1 than those in CB6r2 and CB6r3 in this scenario. Moreover, HCHO predicted by CB6r1 was found to be larger than those predicted by CB6r2 and CB6r3, which is caused by an enhanced dependence of HCHO on the emission of isoprene in CB6r1. Regarding NOx, it was found that CB6r1 gives a higher value than the other two mechanisms, which is caused by the relatively stronger connection between the NOx prediction and the release of NO and NO2 in CB6r1 due to the change in the product of the reaction between isoprene and NO3 in CB6r1. Consequently, more emitted NOx is involved in the reaction system denoted by CB6r1, which enables a following NOx formation and thus a higher NOx prediction of CB6r1.

Sensitivity analysis of isoprene and aerosol emission in a suburban plantation using long short-term memory model

Plants emit volatile organic compounds (VOCs), which undergo photochemical reactions to generate secondary organic aerosols and cause ozone (O3) accumulation; thus, they are the focus of urban pollution control strategies. Although some studies on biogenic VOCs and aerosols have been conducted, their environmental effects at the community scale are uncertain, particularly in suburban areas where abundant vegetation and pollutants coexist. Simple data processing methods cannot well address complex environmental conditions, whereas the long short-term memory (LSTM) model can learn relationships between research objects autonomously, thus enabling the analysis of influencing factors. Therefore, we collected 11 indicators of isoprene and submicron aerosol (PM1) concentrations, as well as other pollutants and meteorological factors, for six consecutive months in a suburban plantation in Shanghai. On the basis of correlation and redundancy analyses, LSTM was used to determine the main environmental factors influencing isoprene and PM1 concentrations. The results showed that nitrogen oxides (NOX), O3, photosynthetically active radiation (PAR), and temperature had the highest influence. The reactions between NOX, O3, and isoprene, PM1 are complex, and high levels of both isoprene and NOX in suburban areas may favor O3 production. PAR and temperature control the emission and photooxidation of isoprene and influence their conversion from a gaseous state to a particulate state. Considering the complex atmospheric environment, this study analyzed the sensitivity of isoprene and PM1 to environmental factors by artificial intelligence method. It demonstrated the effectiveness of LSTM for analyzing complex time-series data with unknown mapping relationships, which provided solutions for large-scale studies. And the results provided a scientific basis to further explain the mechanism through which influencing factors affect suburban communities and to control suburban air pollution.

Experimental demonstration of NOx reduction and ammonia slip for diesel engine SCR system.

This paper investigates the characteristics of selective catalytic reduction (SCR) with a V2O5-WO3/TiO2 catalyst by studying the key parameters and determining a method for controlling ammonia injection with a sample test bench. Four parameters are defined and adopted to represent the characteristics of nitrogen oxides (NOx) and the ammonia reaction. The effects of NH3/NOx ratio (NSR), catalyst temperature, and ammonia injection period on NOx conversion efficiency and ammonia slip are investigated. The correlation between ammonia slip and ammonia saturation storage level is studied. The experimental results show that the ammonia saturation storage level has a great impact on NOx reduction and ammonia slip. The NOx conversion efficiency and ammonia slip strongly depend on the ammonia saturation storage level. Under such conditions, the NOx conversion efficiency is best when the ammonia saturation storage level is 68.2~73%, and the value reaches 75% before ammonia slip. Pulse injection improves the NOx conversion efficiency and limits ammonia slip. Comprehensive comparison shows that the injected ratio of NH3/NOx is first larger and then smaller than is beneficial for the rapid improvement of NOx conversion efficiency; the appropriate NH3/NOx ratio and continuous injection time must be controlled, or it is easy to cause ammonia slip. Therefore, a control algorithm based on ammonia storage saturation level has been proposed. According to the difference between the actual value of ammonia storage saturation and the target value, the controller corrects the injection of urea to achieve control of ammonia storage saturation level. The period of pulse injection has little influence on the mean value of NOx at the outlet; however, it affects the peak level of NOx and ammonia slip. Using varied period pulse injection further improves the NOx conversion efficiency and restrains ammonia slip. The outlet level of NOx can be reduced by adopting a suitable ammonia pulse injection interval.

Microencapsulated phytogenic in dog feed modulates immune responses, oxidative status and reduces bacterial (Salmonella and Escherichia coli) counts in feces

Improving the health and immunity of pets is a concern of the guardians, while maintaining the health of the animals directly impacts the owners' health and public health. The objective of this study was to produce a dog feed containing a microencapsulated phytogenic blend, as well as determine the impact of the additive on animal health and its intestinal microbiota. The composition included microencapsulated thymol, carvacrol, and cinnamaldehyde, at 300 mg/kg of feed. Ten male beagle dogs were divided into two groups, identified as follows: the control group (C; ingested the feed without the additive) and the treated group (T; consumed feed containing the phytogenic blend). The dogs received 300 g of feed/day divided into two meals. Greater neutrophil counts in group T and lymphocyte counts were observed at the end of the experiment, as well as levels of α2-globulins and γ-globulin, while β1 and β2-globulins levels were lower in group T. Serum nitrogen oxide levels were higher in group T. Levels of reactive oxygen species were lower in group T at days 30 and 45, unlike activity of glutathione peroxidase that was higher. We found less bacterial contamination in the feces of dogs in group T, i.e., total bacterial count, total coliform counts, and counts of Salmonella and Escherichia coli were lower on days 30 and 45. Phytogenic blend intake reduces bacterial counts in stool and improves antioxidant/oxidative status and immune responses.

Experimental and low-dimensional numerical study on the application of conventional NOx reduction methods in pulse detonation combustion

Although research interest in pressure gain combustion (PGC) remains high, information on pollutant emissions from detonation-based devices such as pulse detonation engines is sparse, especially lacking extensive experimental parameter studies. Nevertheless, available results indicate potentially very high exhaust levels of nitrogen oxides (NOx) due to the significantly increased combustion temperatures and pressures induced by the detonation wave. To counter this issue, this study applies conventional NOx reducing measures in the form of fuel-lean mixtures and nitrogen dilution (emulating exhaust gas recirculation) to a pulse detonation combustor in multi-cycle operation. Their impact on the exhaust gas composition is measured and compared to numerical predictions by two available simplified models. To allow for a broader range of comparison and better assess the capabilities of these numerical models, emissions from fuel-rich and oxygen-enriched mixtures are measured as well. Experimental results confirm high levels of NOx up to several thousand ppm for near-stoichiometric, undiluted mixtures. When conventional NOx reduction measures are applied, significant NOx abatement can be achieved, with further reduction potential primarily limited by unsuccessful deflagration to detonation transition (DDT). Comparison with numerical results shows that simplified models allow for good qualitative agreement and can also deliver good quantitative predictions over a wide range of conditions if a suitable heat-loss model is chosen.

Assessment of Ozone and Nitrogen Oxides Variations in Urban Region of Patna, India

Increasing levels of ozone and nitrogen oxides may have damaging effects on the ambient environment, vegetation, public health and climate. Therefore, ozone chemistry is crucial to understand in fast-growing urban regions. This article reports on the determination of ozone and nitrogen oxides in the urban region of Patna, India. The aims of present study involve temporal variations of gaseous pollutants and source analysis. The occurrence of pollutants is dependent on meteorological factors along with local and distant sources. The findings may be useful for policymakers to formulate effective pollution-reducing strategies in the case of the new fast-growing urban city.